Before the United States Constitution, there was the Articles of Confederation. The Articles were very weak and gave little to no power to the government.
People in favor of the Articles of Confederation were called Anti-Federalists, they wanted the power to be in their own hands and feared a strong government. On the other hand, people who wanted to amend the Articles of Confederation were called Federalists, they wanted to have a strong government.
The Constitutional Convention of 1787 was called and the Articles of Confederation were going to be reworked. While this was the original plan, the Articles of Confederation ended up getting scrapped and the United States Constitution was created instead. The Anti-Federalists were not very happy about this and feared that their rights were going to be taken away. They demanded to have a Bill of Rights in order to protect their rights from the government.
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Some protections that were granted under the Bill of Rights were:
The First Amendment. Protection of freedom of speech, press, petition, and assembly. Also grants freedom of religion. This is very important for individuals to have, as the government can not stop them from having their own freedom.
The Second Amendment. The right to bear arms. This is very important as well, as individuals could protect themselves in case the government became tyrannical.
The Third Amendment. Protects citizens from having to house troops. This was a huge problem during the Revolutionary War. Citizens would be forced to house and feed British troops. This is important because it protects individual's privacy and homes.
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There are many more Amendments that protect individuals' rights, these are just a few.